This invention relates in general to disposable containers and deals more particularly with an improved disposable biodegradable insulated container particularly adapted to contain hot liquids and to a method for making such a container.
Insulated containers made from plastic material for handling hot liquids such as beverages, soup and the like have enjoyed great popularity, particularly in the fast food industry. However, such containers, and particularly those molded from foam plastic materials, are not biodegradable, present difficult disposal problems, and must be separated from recyclable waste materials before the latter waste materials may be reprocessed. Recent legislative trends prohibiting the use of such environmentally unfriendly products have created a need for improved disposable containers which are both recyclable and biodegradable.
Disposable insulated paper cups which have heretofore been available are generally of a dual wall type or comprise an inner container and an outer covering of corrugated material having a deeply furrowed outer surface characterized by a series of contiguous curved ridges and hollows. A typical example of such a cup assembly is found in Shikaya U.S. Pat. No. 3,908,523. The latter cup assembly includes a substantially conventional cup received within an outer corrugated sleeve. While such a cup assembly may possess the desired insulating qualities, the outer surface of the assembly is not particularly suited to carry printed material, such as a listing of the ingredients in or directions for use of a product packaged in the container. Further, such a cup assembly is relatively expensive to manufacture, because a substantial quantity of paper is required to make the corrugated outer sleeve. A relatively large quantity of adhesive is also required to make each cup assembly, since it is generally necessary to secure all of the corrugations to the surface of the inner container. The exposed corrugations which define the outer surface of the cup assembly are easily damaged or crushed by ordinary handling which may result in an unsalable product. Further, the exposed corrugations tend to cause jamming when a cup assembly is nested within another cup assembly of like kind.
Accordingly, it is the general aim of the present invention to provide an improved disposable biodegradable insulated container for low cost manufacture and which is suitable for carrying printed material which may be easily read, may be nested without difficulty within another container of like kind, and which closely resembles a conventional smooth surfaced container while possessing insulating qualities equal to or better than those of comparable containers.